Some people are worried that radio waves used by mobiles to send and receive calls and messages are linked to health problems. But there's currently no evidence of this.
Dr Jewell reckons more research needs to be done. "It is always better to be safe than sorry," he said.
Leah and Sonali spoke to Dr Ranj Singh, who advised: "I think it would be sensible to try and limit the amount of time you spend with the phone close to your head and yes texting may actually be safer [than calling]."